1. Field of the Invention
The present invention relates to a construction machine such as a hydraulic excavator in which an exhaust structure from an engine room is improved.
2. Description of the Related Art
FIGS. 8 and 9 show a hydraulic excavator to which the present invention is applied.
The reference numeral 1 denotes a crawler type lower traveling body. On the lower traveling body 1, is mounted an upper rotating body 2 rotatably around a vertical axis. In an upper frame 3 of the upper rotating body 2, are installed a working attachment 10 including a boom 4, an arm 5, a bucket 6, a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9 (hydraulic cylinders) for operating the boom, the arm and the bucket, a cabin 11 and the like.
On a rear part of the upper frame 3, is disposed an engine room 12 whose periphery is covered by a guard member (reference numeral thereof omitted). In the engine room 12, are installed an engine 13, devices around the engine 13 (a radiator 14, a cooling fan 15, a hydraulic pump 16 and the like). In FIGS. 8 and 9, the reference numeral 17 denotes a counterweight which also serves as the guard member on the back surface side.
In an upper surface part of the engine room 12, is disposed a bonnet 18 openably taking the rear side as a support point on a central part in the lateral direction. By opening the bonnet 18, maintenance of the engine 13 and the like is performed from the upper surface side of the engine room.
Meanwhile, as an access passage for the maintenance from the upper surface side of the engine, up and down steps 19 for going up are provided on the right side of the upper rotating body 2 (on the right side seen from an operator seated in the cabin 11, the lateral direction described hereinafter will be the same), and a step (shown by a diagonal line) 20 as a foothold for maintenance work is provided on the left side of a top of the steps 19 and just on the front side of the engine room 12. Therefore, a worker is able to go up the up and down steps 19 onto the step 20 from the front side of the machine as shown by double line arrows in FIG. 9, for opening and closing the bonnet 18 and performing the maintenance work.
On a peripheral wall of the engine room 12, are provided an intake port and an exhaust port (not shown). By rotation of the cooling fan 15, as shown by dashed line arrows in FIG. 9, the outside air is taken into the engine room 12 and exhausted to the exterior after a heat exchange operation.
In the above-mentioned construction, a point that the step 20 for the maintenance work is provided just on the front side of the engine room 12 is disclosed in Japanese Patent Laid-Open No. Hei11-200415.
Further, in a small excavator, a technique that in order to improve an exhaust and cooling efficiency, a duct (auxiliary opening) opening toward the outside of the engine room is provided in an outer periphery of the cooling fan is disclosed in Japanese Patent Laid-Open No. 2005-248505.
Particularly in the small type excavator, a surface area of the peripheral wall of the engine room is so small that size of the exhaust port is limited. Therefore, there is a problem that the exhaust and cooling efficiency is basically not sufficient. With regard to this point, as shown in Japanese Patent Laid-Open No. 2005-248505, addition of a duct for exhaust in the vicinity of the engine room is an effective countermeasure.
However, in the small type excavator originally having no extra space, a space for the addition of the duct is limited and only a small duct can be provided. Therefore, it is not possible to improve the exhaust and cooling efficiency as expected.
Further, built-in of the duct itself is troublesome so that an assembling performance of the machine is worsened, and addition of an exclusive duct increases the number of parts. As a result of the above-mentioned facts, there is also a problem that cost is increased.